Sheet material



E. A. CORBIN, JR., ET A1. 2,123,180

July 12, 1938.

SHEET MATERIAL Filed NOV. 20, 1934 im@ N@ SNN @@@rnw Wao Patented July12,- 1938 PATENT OFFICE SHEET MATERIAL Elbert A. col-bin, Jr., Gradyvme,and auwooa w. Wolf, Philadelphia, Pa., assignors of one-third to WilliamC. Biddle, Lansdowne, Pa.

Application November 20, 1934, Serial No. 753,812

1 Claim.

Our invention relates to a new and useful sheet material and method ofmaking the same whereby a thin, transparent or-translucent, water-proofsheet material is used. of the type now generally (ised for wrappinggoods on display counters hermetically to seal the goods and at the sametime to display the same to the best advantage.

.j There is at present available on the market thin, transparent sheetmaterial known as cellophane" which is generally a glycerinated sheet ofregenerated cellulose which is extensively used for wrapping all kindsof merchandise, such as candles, cigars, cigarette packages, shirts,stockings. handkerchiefs, etc., this sheet material being however onlywater repellent or resistant, but not watebproof, and being relativelyexperidive'due to the cost involved in the complicated l chemicalmanufacturing steps by which this sheet l rhV al is produced.Furthermore, the sheet m al referred to is of a limited toughness andflexibility. j It is the object of our invention to produce a sheetmaterial of this character which is waterproof and which possesses greattoughness and resiliency andwhich can be made at much less y cost thansheet material of this type now available.

Our invention also relates to the novel method of manufacturing ournovel sheet material by means of a continuous process utilizing readymade', relatively inexpensive ingredients, thus obviating the necessityof expensive and complicated chemical processes. l

The accompanying drawing is a diagrammatic representation of the form ofmachine by means of which our novel continuous process of making thesheet material formingl the subject of 'our in# vention may be carriedout.

Our novel transparent sheet material is formed of a body substance, aglossing substance, and a water-proofing, resilient andstrengthening-substance' either intermingled in the originalcompositionor applied together successively to form ',lahilnations ofthin lms of the substances used in any desired order. In actual practicewe have fcundthat liquid `latex or-a similar compound may be used to addstrength and resiliency to the finished sheet material as well asthoroughly and positively to water-proof the finished product. We alsfound that a gelatine or ,similar com l)Sound is an inexpensive,convenient and practical body substance which can be utilized to givethe sheet material the desired thickness-and we also found that shellacor a similar drying Il glossy compound can practically and convenientlybe used to give the outer surface ofthe sheet material the desiredfinished and lustrous appearance. In carrying out our invention wepreferably utilize a continuous belt, one face or surface of which ismade to dip into or pass through a series or succession of vatscontaining the diiferent ingredients of which the sheet material is tobe made, properly arranged, whereby a film is formed on said belt, whichfilm when stripped of thebelt constitutes a sheet material of ourinvention. n f

In order more clearly to illustrate our invention, we refer to theaccompanying drawing in which I designates a continuous belt whichpasses through an aperture 2 in the working platform or floor 3 of theroom and under the roll 4, over one or more rolls 5, under the roll E,over the roll 1, underthe roll B, over the roll 9, and under the drumI0. Under and registering with the drum I0 is a tub I2 adjustablymounted on the leg Il and containing one of the materials used informing the sheet material of our invention in a liquid form, which inthis instance is shellac I5. The outer'surface I6 of the belt I is thencoated with a nlm of shellac, the thickness of which can bepredetermined by the nature of the surface IB of the belt I, theviscosity of the liquid I5, as well as the rate of travel of the beltduring its contact with the liquid I5. The illm thus `formed on thesurface I6 of the belt I is so thin as not to per-v mit illustration inthe drawing, since the finished product is perhaps less thanone-thousandth of an inch thick. The belt I then enters the heatingchamber or oven I8 through the aperture I9 and passes alternately overand under the rollers 20 and 2 I, respectively, and emerges from thechamberV I8 through the aperture 22. The chamber ldlmay be heated bymeans of the heating elements 23 or the rollers 2|) and 2I maythemselves be made hollow and supplied with steam, hot air or otherheating medium. In the heating cham` ber I8 the film of shellac appliedto the surface I6 of the belt I is dried by the heat from the chamber I8and is calendered by its passage over and under the rolls 20 and 2i. Thebelt I then passes over the guide roll 2li, under the guide rolls 25,over the guide rolls 26, and under the next adjacent drum 21, to come incontact with the liquid 28 in the vat or tub 29, which liquid in thisinstance is preferablyV a solution of gelatine calculated to give bodyto the sheet material to be formed. After being coated with a lm of agelatinous solution the belt enters the heating chamber 3U which is alsosupplied with the rollers 2li and 2| and which is similarly heated, sothat when the film of gclatlnous solution deposited on the belt is driedand calendered the belt emerges from the chamber 8l and goes over andunder similar rolls 2l, II and Il to pass under the drum 3l and comeinto contact with the liquid Il in the vat ll, which in this-instance isliquid latex or other solution of rubber or waterproofing substance,whereupon the belt enters the heating chamber It where this film biwaterproofing material is also calendered and dried over the-films ofgelatinous and lustrous substances already deposited' on the belt duringits passage through the vats I2 and 2l. In order to make a balancedsheet, that is one ot a symmetrical construction so as to` preventcurling and warping of the sheet in` manipulation and use, we deposit asecond film of gelatinous substance 28 in a second vat 2l, and a secondnim of shellac or lustrous substance it in a second vat i2. it beingunderstood that the added aims of gelatinous and shellac substances arealso dried and calendered in the heating chambers Il and ll'which arealso provided with the rolls 20 and 2| in the same manner as the heatingchambers Il and 3l. When the belt finally emerges from the heatingchamber 3l through the outlet opening It, the sheet material Il composedof the central rubber or waterproofing solution Il, the films ofgelatinous or bodyl substance 2l on either side thereof and the outerfilms of shellac or other lustrous substance Il is peeled of! the beltand rolled on .a take-up roll (notshown). 'I'he belt I may becontinuously driven by means of the drums I ll, 21 and il which arepropelled by any suitable means (not shown), or separate driving rolls(not shown) may be employedat either or both ends of the apparatus topropel the belt, if so desired.

While we have found in practice that five "dippings, as shown, namely:the two outer shellac layers, the two intermediate gelatine the centralrubber or other waterproofing layer, are suflicient to produce the sheetmaterial of our invention, and while it is within the scope of ourinvention to vary the thickness of the sheet material produced byregulating speed of travel oi' the belt, by changing the surface tensionproperties of the face of the belt, or by regulating the viscosity ofthe various liquid ingredients used. it is to be understood that it isalso within the scope of our invention to use any number of vats andsubject the belt to any desired number of "dippings so as to produce athicker or thinner sheet at will.

Also, while we have shown our invention as consisting in placing on thebelt I successive layers or lms of lustrous, gelatlnous and rubbersolutions, it is within the scope of our invention to mix the rubber orwater-proofing substance with the gelatinous or body forming substancein the same vat to form a single film of the desired thickness, whichfilm is provided with outer surface coatings of any lustrous substanceto give it thehecessary finish.

v either side of the central rubber layers, and

While we have found in practice that shellac 'gives the 'proper luster,that gelatine forms a lood body ingredient, and that liquid rubber formsan adequatewater-proonng element, it is to be understood that otheringredients which have waterfprooiing qualities, which would constituteflexible and transparent body substances. and which would give theproduct the necessary finish, can be used ywithout departing .from thespirit or scope oi' our invention.

It is to be understood that it it is desired to produce a colored sheetmaterial according to bur invention it is merely necessary to introduce'a dye or combination of dyes into one or more of thevsubstances ofwhich the finished product is formed, thus producing a sheet materialhaving -a's it is turned out and by replenishing the cons' tents ofthevats I2, 29 and 35. In carryingaut our process we found it advisable toseparate the various heating chambers Il, l0, It, il and Baby suitablepartitions 42 in order to enable us toy regulate the drying capacityv ofeach. heating chamber in accordance with the requirementyof theparticular substance the film of which is to, be dried in the particularchamber. c,

Tne -gelatinous films or coatings employedv on. film. or coating inaddition to giving the finished sheet the necessary body also provide asurface having the neces-- sary tension or cohesion to insuretheunii'orm spreading and adhesion of the rubber nlm. l

By utilizing the central rubber film with the, outer sheliac films andthe intermediate gelati-, nous films or their equivalents we produce,-al balanced sheet, that is, one having a, svinmetrical cross section,thereby insuring that, the. sheet will remain fiat in use andeliminating the possibility of the sheet curling or warping. It will beseen that our novel product lcan be, made at a very low price, due totheveryiow cost of the ingredients utilised,y and that the continuf, ousprocess ofI forming the sheet material and, taking it ofi' from the beltpermits oi constant operation and greatly reduces the cost of manu-i,facture asl compared with the manui'actlireosi-14 other synthetic sheetsheretofore known I which are produced by the extrusion process. whichinf-,f volves the use 'of very exact and expensive ma, chinery, if athin, uniform product iste be made. We claim: i y A composite wrappingsheet material compris-i in integrated form, a central layer ,formed ofa rubber compound, outer layers formed cfa water-prooiing resinoussubstance, and layers-of an adhesive gelatinous substance intermediateand inter-connecting the opposite-.sides oLsaid. central layer with saidouter layers.

ELBERT A. CORBIN, Jn. ELLWOOD W. WOLF.

Iiii.'

